So why would I switch?Ah, the infamous question. Since you asked, there are many, many good reasons to switch. I'll just name a few off the top of my head:
1. Backup - What happens if the one and only browser you have installed is compromised and you have no net access? What if an upgrade goes bad? (This happens more often than many people realize.) It never hurts to have something else available in such events. It is unwise to have just one browser, regardless of preference. Besides, you can run multiple brands of browsers simultaneously without any problems. I do all the time.
2. Security - This pretty well speaks for itself. Having an "OS component" that browses the web is just asking for problems. IE still has numerous unpatched security holes as we speak that have gone on for several months. Opera has a much cleaner track record.
3. Freedom - Why stick with just one browser? Or one OS? Or one of anything for that matter? It never hurts to try. Why settle for what comes bundled with the OS? BTW, Opera is now free, like Firefox.
4. Options - Opera is loaded, and I mean loaded with options, many of which are quick and easy to access. Don't like the style of a web page? One click can change that. Don't like those ads? Again, a click away. Want to arrange your toolbars the way you want? Want to remove buttons you don't use? No problem. Heck, you can make the Back button function as something else while it's inactive, or even remove it altogether if you really wanted to.
I could go on and on, but this post is already long enough. :)